At present, numerically controlled turret punches have gained wide acceptance in the field. Such turret punches are operable to accurately punch in a high speed manner a wide variety of hole designs and positions without any operator input aside from the initial positioning of the workpiece and moveable clamps, and programming of the numerical control means. However, there is a need in the industry for relatively inexpensive automatic feeding and withdrawal means for the workpieces for certain types of jobs, so that one operator may operate a plurality of turret punches at the same time. In addition to being inexpensive, such loaders and unloaders for which the need exists must be adaptable to a wide variety of sizes of sheet metal pieces to be punched, must be portable, must be simple, and should be adaptable for numerical control. A common numerical control is thus able to feed the work pieces into position, automatically punch them to produce a finished workpiece and the desired hole configurations, remove the workpiece from the table and stack it, and continue this operation until all of the workpieces in the loading stack are exhausted, without any operator input being necessary during the cycle.
According to the present invention, an automatic workpiece feeding assembly has been provided for a numerically controlled turret punch or the like that satisfies the above needs. The assembly according to the present invention is utilizable with virtually any conventional numerically controlled turret punch (or like structure) on the market today, including those made by Warner and Swasey (i.e. the Wiedematic W-2040, W-3050, or W-4560), Di-Acro (i.e. QCT-20, VT/19), Strippit (i.e. Fabri-Center 1000 II), Behrens (Performance Plus series), etc.
The assembly according to the present invention includes a loader magazine having an adjustable volume for receiving a stack of workpieces to be fed to a turret punch or the like; ejector means associated with the loader magazine for horizontally feeding workpieces one at a time in a feed direction from the loader magazine receiving volumes to a turret punch or the like into operative association therewith; an unloader magazine having an adjustable volume for receiving a stack of workpieces to be received from a turret punch or the like; and automatic means for controlling the loader magazine and unloader magazine to transfer each workpiece in a stack from the loader magazine to the turret punch or the like, and to the unloader magazine. Power means may be associated with locator stops on the turret punch table for moving the stops vertically between positions above and below the table, and for moving the stops horizontally toward and away from the clamping means associated with the turret punch, so that a workpiece engaged by the locator stops may be moved from a position horizontally spaced from the clamping means into operative association with the clamping means.
The adjustable volume for receiving a stack of workpieces for each of the said loader and said unloader magazine preferably comprises first and second side walls disposed generally parallel to the direction of feed of workpieces from or into the magazine, means for automatically adjusting horizontal spacing between the first and second side walls, workpiece support members associated with each of the side walls, means for automatically vertically moving the workpiece support members with respect to the side walls, a third side wall member disposed generally perpendicular to the direction of feed of workpieces from or into the magazine, and means for automatically horizontally moving the third side wall member in and opposite to the direction of feed. The ejector means preferably includes a moveable ejector plunger for engaging the top workpiece in a stack in a loader magazine, and means for operatively mounting the ejector plunger on the third side wall; and two pairs of rollers operatively mounted to the first and second side walls at the front portions thereof, including power means for driving the rollers to continue feeding of a workpiece grasped thereby in the feed direction. Similar rollers are also mounted on the unloader magazine for engaging a workpiece from the turret punch and power the workpiece into operative relationship with the stack of workpieces in the unloader volume.
The automatic control means for controlling the loader magazine and unloader magazine to transfer each workpiece in a stack from the loader magazine to the turret punch and to the unloader magazine preferably comprises numerical control means--preferably the same numerical control means utilized for controlling the turret punch. The numerical control means operates to activate the ejector means to move the top workpiece in the stack in the loader magazine into operative association with the turret punch, activates the means for vertically moving the workpiece support members of the loader magazine to position the next workpiece in the stack into position to be acted upon by the ejector means, activates the unloader magazine workpiece support members to lower the top workpiece in the stack to receive another workpiece thereon from the turret punch and activates the workpiece engaging means associated with the unloader magazine for moving a workpiece from the turret punch onto the stack in the unloader magazine. The locator stops on the turret punch table are also controlled by the numerical control means, and the means for positioning the first, second, and third walls of the magazines with respect to each other may also be numerically controlled. Both magazines preferably are mounted on casters so that they may be moved into position when the automatic feed capability is desired, and moved out of position for use of the turret punch in a conventional manner.
It is the primary object of the present invention to provide a relatively inexpensive practical automatic workpiece feeding system for a numerically controlled turret punch or the like. This and other objects of the invention will become clear from an inspection of the Detailed Description of the Invention, and from the appended claims.